/*
Copyright 2003-2012 Dmitry Barashev, GanttProject Team

This file is part of GanttProject, an opensource project management tool.

GanttProject is free software: you can redistribute it and/or modify 
it under the terms of the GNU General Public License as published by
 the Free Software Foundation, either version 3 of the License, or
 (at your option) any later version.

GanttProject is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
GNU General Public License for more details.

You should have received a copy of the GNU General Public License
along with GanttProject.  If not, see <http://www.gnu.org/licenses/>.
*/
package net.sourceforge.ganttproject.util;

import java.awt.Font;
import java.awt.Graphics2D;
import java.awt.font.FontRenderContext;
import java.awt.font.TextLayout;
import java.awt.geom.Rectangle2D;

/**
 * Contains methods to calculate the text length
 *
 * @author bard
 */
public class TextLengthCalculatorImpl implements TextLengthCalculator {
    private Graphics2D myGraphics;

    private State myState;

    public TextLengthCalculatorImpl(Graphics2D g) {
        setGraphics(g);
    }

    public void setGraphics(Graphics2D g) {
        myGraphics = g;
        myState = null;
    }

    /** @return the length of text for the given g */
    public static int getTextLength(Graphics2D g, String text) {
        if(text.length() == 0) {
            return 0;
        }
        FontRenderContext frc = g.getFontRenderContext();
        Font font = g.getFont();
        TextLayout layout = new TextLayout(text, font, frc);
        Rectangle2D bounds = layout.getBounds();
        return (int) bounds.getWidth() + 1;
    }

    public int getTextHeight(Font f, String s) {
        Font existing = myGraphics.getFont();
        myGraphics.setFont(f);
        int result = getTextHeight(s);
        myGraphics.setFont(existing);
        return result;
    }

    @Override
    public int getTextHeight(String text) {
        return (int) myGraphics.getFontMetrics().getLineMetrics(text, myGraphics).getAscent();
    }

    @Override
    public int getTextLength(String text) {
        return getTextLength(myGraphics, text);
    }

    @Override
    public Object getState() {
        if (myState == null) {
            myState = new State(myGraphics.getFontRenderContext(), myGraphics
                    .getFont());
        }
        return myState;
    }

    /** Internally used class containing unique variable for the current state */
    private static class State {
        // Internal values determining the uniqueness of the state
        FontRenderContext context;
        Font font;

        State(FontRenderContext context, Font font) {
            this.context = context;
            this.font = font;
            assert context != null;
            assert font != null;
        }

        @Override
        public boolean equals(Object o) {
            State rvalue = (State) o;
            if (rvalue == null) {
                return false;
            }
            return rvalue.context.equals(this.context)
                    && rvalue.font.equals(this.font);
        }

        @Override
        public int hashCode() {
            return font.hashCode();
        }
    }
}
